andrecg

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I have been working at CEES since January 2011 in collaboration with the Marine Biology group at UiO. As a postdoc I am involved in the interdisciplinary project PhytoSCALE which studies the adaptive responses of coccolithophores to climate change. I carry out culture experiments, both batch and continuous culturing, on different species of these calcifying microalgae to observe changes in phenotype due to changing environmental parameters. I am currently focusing on the effect of nutrient availability on coccolithophore size and morphology. To this end I mainly use microscopy techniques such as polarized light and scanning electron microscopy. Results obtained from culture studies are used to interpret fossil time series data collected by the P.I. of the project, Jorijntje Henderiks at the University of Uppsala in Sweden.

Previously, I carried out my PhD at the Stazione Zoologica in Naples, Italy on the oxylipin metabolism of diatoms. Before that I worked on diatom-copepod interactions at the Biological Station (AWI) on Helgoland, Germany for my graduate thesis. I am interested in microalgal metabolism and the involved regulatory mechanisms, how these may evolve under changing environmental conditions, and the ecological consequences for these organisms.

Diatoms are unicellular microalgae that often dominate marine ecosystems. As photosynthetic organisms they use CO2 and light energy to produce organic matter. A fundamental enzyme in CO2 sequestration and cell growth is Ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO). This enzyme catalyzes the first step in CO2 fixation and has been called the most abundant protein on Earth. RuBisCO enzymes from diatoms have been described as having high specificity and high turnover rates compared to RuBisCO from other photosynthetic organisms. Enzymes from cold-water species tend to have high catalytic efficiency as species adapted to low temperatures have had to modify enzyme structure and function. This in turn would require low concentrations of these enzymes in the cells. Little is know about the RuBisCO of Arctic species, but recent studies suggest that RuBisCO accounts for a minor percentage of total protein in phytoplankton cells. This study is therefore aimed at measuring RuBisCO concentrations in Arctic diatom species using immunological techniques and enzyme specific antibodies. Monoclonal species are grown in large (100 L) tanks under changing environmental parameters to monitor changes in physiology and examine variability in RuBisCO content among species. Diatoms are a renewable resource that can be employed e.g. as feed in aquaculture, as lipid producers for biofuel, and as a source for essential fatty acids and other high value molecules. Knowledge about RuBisCO content and efficiency of different species can help selective productive strains for mass cultivation.

Gerecht, Andrea (2013). Phosphorus limitation does not change the ratio of calcite to organic carbon in Coccolithus pelagicus.

Gerecht, Andrea (2013). Temperature, but not phosphorus limitation, changes the ratio of calcite to organic carbon in Coccolithus pelagicus.